Feb 10, 2012

The Greenland Ice Sheet Melt: Irreversible Implications

Posted by in categories: economics, engineering, existential risks, habitats, sustainability

It is of course widely accepted that the Greenland icesheet is melting at an alarming rate, accelerating, and is an irreversible process, and when it finally does melt will contribute to a rise in sea levels globally by 7 meters. This is discounting the contribution of any melt from the West Antarctic ice sheet which could contribute a further 5 meters, and the more long term risk of East Antarctic ice sheet melt, which is losing mass at a rate of 57 billion tonnes per year, and if melted in entirety would see sea levels rise by a further 60 meters.

In this light it is rather ‘cute’ that the site here dedicated to existential risks to society is called the Lifeboat Foundation when one of our less discussed risks is that of world-wide flooding of a massive scale to major coastal cities/ports & industries right across the world.

Why do we still continue to grow our cities below a safe limit of say 10 meters above sea level when cities are built to last thousands of years, but could now be flooded within hundreds. How many times do we have to witness disaster scenarios such as the Oklahoma City floods before we contemplate this occurring irreversibly to hundreds of cities across the world in the future. Is it feasible to take the approach of building large dams to preserve these cities, or is it a case of eventually evacuating and starting all over again? In the latter case, how do we safely contain chemical & nuclear plants that would need to be abandoned in a responsible and non-environmentally damaging procedure?

Let’s be optimistic here — the Antarctic ice sheets are unlikely to disappear in time scales we need to worry about today — but the Greenland ice sheet is topical. Can it be considered an existential risk if the process takes hundreds of years and we can slowly step out of the way though so much of the infrastructure we rely on is being relinquished? Will we just gradually abandon our cities to higher ground as insurance companies refuse to cover properties in coastal flooding areas? Or will we rise to a challenge and take first steps to create eco-bubbles & ever larger dams to protect cities?

I would like to hear others thoughts on this topic of discussion here - particularly if anyone feels that the Greenland ice sheet situation is reversible…


Comments — comments are now closed.

  1. vin says:

    IMHO worst case scenario would be a rapid acceleration in the time scale of the Greenland ice melt. When where and how it will happen, nobody knows, but for us to think it’s okay to keep dumping CO2 into the atm at this pace shows that we are already probably too late. I think predictions are only going to get worse in the next 5 to 10 years, and I believe that in my lifetime I will witness mass evacuation. FYI I’m 24.

  2. symbolset says:

    The Greenland ice sheet situation IS reversible. And it’s being reversed right now. They’ve cored it to bedrock and found that 12,000 years ago there was no such thing as a Greenland ice sheet. It was too warm there for it to exist. Now it seems it’s going away again — no doubt much to the benefit of people who live in Greenland.

    Yes, sea levels will rise and cities ought not be built so close to the sea. But that’s a local zoning issue for all but a handful of low-lying islands. The oceans will not leap up and wash Manhattan away overnight. These things take time.

  3. jimmy says:

    Rice is a very important grain crop. The rice growing deltas of the world are home to millions and grow food for billions. Those deltas average about 1 meter above sea level. We don’t have to wait for total sea level rise, a good storm surge will salinate the deltas effectively enought that no rice will be grown long before the total sea level rises. Famine is lurking.

  4. JohnHunt says:

    Tom, I don’t count sea level rise as reaching the level of existential risk. The usual understanding of the term “existential risk” is that it risks the death of 100.0% of the human population. In your post, you suggest that the ocean level rise would take hundreds of years. It would be most the most unreasonable situation for 100.0% of people to travel to the shore and intentionally wait hundreds of years while the ocean slowly rises above their nostrils just so that they can die. Rather, insurance rates would rise, people would start building sea walls and expanding inland cities. So there would be an economic loss of old buildings but certainly not a direct existential risk.

    BUT, giving you the benefit of the doubt, you would probably say that the existential risk is indirect. But if so, you need to specify how you think that would work. Or, alternately, you would agree that it is not a truly existential risk but just potentially a very bad (even an unacceptable) loss of human life (say at least 10% of the human population). But if this is what you are saying then please be clear about it. If so, my preference is that the Lifeboat Foundation and this blog focus on the truly existential risks because I think such risks are very real and far far worse an outcome than anything less.

  5. JohnHunt says:

    Some more thoughts, do you require into account likely chances in or consumption of energy? Are the predictions based only upon correct levels of CO2 or in expected future production? If so then those predictions are not taking into account peak oil, depletion of fossile fuels, transition to fusion energy, growth of nuclear power internationally, solar, wind, wave, biofuel, efficiencies, etc.

    Also, I understand that the graph of ocean level rise is very linear and does not seem (to me) to correlate to the somewhat accelerating level I if CO2. So, might ocean level rise more attributed to other factors such as the rebound of land after the last ice age?

  6. Tom Kerwick says:

    Symbolset, a global 7 meter sea rise would surely affect most/all harbor cities around the world for example so hardly just a local zoning issue. I don’t know what sea levels were 12,000 years ago that you refer to but we did not have large coastal cities or industries like we have today back then to worry about the impact of rising sea levels on. Here’s a useful website illustrating the impact worldwide:

    John — yes I was not suggesting extinction, so existential is an incorrect word to throw around in this context but I was suggesting an eventual problem to the existence of a lot of regions. You would be surprised at how many coastal cities have areas within 10 meters of sea level, and how many of such cities are a hub to their regions.

    As it is a global risk to how society functions, and also a rather inevitable one, I think it is one which is worthy of discussion on the Lifeboat Foundation blogs.

  7. G KING says:

    The real threat is not the ice melt and the rise of the water, but the effect on the Atlantic Ocean’s water current system that regulates our global weather. The impact is already being felt this year with winter temperatures averaging 40 degrees in New England and the below average temperatures in Europe for example. The global weather system will have a greater and more effective impact world wide much sooner than the implications of rising sea levels will.

  8. Tom Kerwick says:

    It is difficult to attribute localized climate fluctuations directly to any global issue such as this, particularly when (please correct me if I am wrong) we have not yet witnessed major changes in ocean water currents, but I appreciate your point. Taking the point well worded directly from Yahoo answers ‘Currently the Atlantic ocean conveyer drives the warm waters of the Gulf Stream north, where they eventually cool and increase in salinity, thus sinking and returning south. Should the Arctic ice melt, this process may be seriously affected, consequently affecting the climates of western Europe and the eastern seaboard of north America’. Anyway, this is attributable to all of polar ice melt, not just the Greenland ice sheet. Additional consequences of Greenland ice sheet melt are more specific — and although, yes, less imminent — hardly less severe.

    The point I would like to underline here, as it is often overlooked, is that the melt of ice from the Greenland ice sheet is very different to other polar ice melt that we witness in the northern hemisphere. Melt of the entire north polar sea ice would not cause global sea levels to rise significantly — due to the nature by which ice expands to occupy the area of water it displaces. The difference, of course, with the Greenland ice sheet melt, is that the ice is all over land, and so all melt contributes to rises in sea level worldwide.

  9. Rich Wright says:

    I’m interested in your position on the recent Times World Atlas issue where it was claimed that the Greenland Ice had disappeared in areas, but where satellite photos showed ice to still exist. Many persons, including scientists, objected to the Times World Atlas depiction of the situation.

    Has’t the Times World Atlas admitted they made an error, and that the changes that have occurred over the past 12 years are very insignificant?

    What is your view on this incident?

  10. Tom Kerwick says:

    Richard — I’m actually not overly familiar with the incident, as to what extent the Times World Atlas portrayed the ice sheet to have completely disappeared in areas — but one cannot say just that the ice is there or the ice is not there, as we are dealing with the melt of a very thick ice sheet — If the ice is depleted to 200 meters in some parts where before it was 2,000 meters then the satelite photos would show ice still exists but that would not imply that the changes over recent years were insignificant. Was the print in the Times World Atlas claimed to be an enviro-political stunt or a genuine error in documenting the current coverage of the ice sheet? Who made demands for it to be admitted/corrected?